EP0934743B2 - Use of a wax microdispersion in cosmetic or dermatological compositions - Google Patents

Description

The invention relates to the use of a wax microdispersion in a cosmetic composition or for the preparation of a dermatological composition for topical application, as an active agent for the prevention and / or treatment of certain signs of endogenous aging and / or exogenous.

Skin aging results from the effects on the skin of intrinsic and extrinsic factors. Clinically, signs of aging result in the appearance of fine lines and wrinkles, sagging skin and subcutaneous tissues, loss of skin elasticity, sluggish skin texture, and yellowing of the skin which becomes duller and without radiance. In areas of the skin that have been exposed to the sun throughout life - mainly the face, décolleté, hands and forearms - pigment spots, telangiectasias and elastosis are common.

Some of these signs are more particularly related to intrinsic or physiological aging, that is to say to age-related aging, while others are more specific to extrinsic aging, that is, to aging. caused in a general way by the environment; it is more particularly photo-aging due to exposure to the sun, light or any other radiation.

Skin changes resulting from intrinsic or physiological aging are the result of genetically programmed senescence involving endogenous factors. This intrinsic aging causes in particular a slowing down of the renewal of the cells of the skin. Histologically, the skin is generally thinned, both epidermally and dermally. The density of fibrous macromolecules of the dermis (elastin and collagen) is decreased. On the contrary, extrinsic aging leads to histopathological changes such as excessive accumulation of elastic material in the upper dermis and degeneration of collagen fibers.

The invention is essentially concerned with wrinkles, fine lines and the radiance of the skin.

Many compositions are known which claim to treat the wrinkles and fine lines of the skin or to firm the cutaneous tissues, but these compositions treat only incompletely and temporarily these morphological disorders. Also, there remains the need for a composition for topical application to treat more effectively wrinkles and fine lines. The invention also makes it possible to give a glow to the aged skin, comparable to that of a younger skin.

The subject of the invention is therefore the cosmetic use of a microdispersion of wax the particles of which have dimensions of less than 1 μm as an active agent intended to prevent and / or treat the appearance of wrinkles and fine lines.

The subject of the invention is also a cosmetic process for reviving the radiance of the skin by treating wrinkles and / or fine lines using a microdispersion of wax whose particles have dimensions of less than 1 μm, applied to the skin in a cosmetic composition.

We know, by the document SU-1335288 , the use of emulsified waxes in compositions for the treatment of loosening of the skin. However, in the compositions described herein, the emulsified waxes are used as an emulsifying agent, their use as active to prevent and / or treat the appearance of the signs of skin aging is neither mentioned nor suggested by this document.

We also know, in particular by the document SU-1250297 , that the waxes can be used in the treatment of aged skin, in particular wrinkles. However, the Applicant has discovered that, unexpectedly, the wax microdispersions have a much higher efficiency than conventional waxes in the prevention and treatment of the signs of skin aging.

Microdispersions of wax, which are stable dispersions of colloidal wax particles, are known and can be prepared according to known methods; see for example " Microemulsions Theory and Practice, LM Prince Ed., Academic Press (1977) pages 21-32 .

The particles of the microdispersion of wax have dimensions less than 7 μm, preferably less than 0.5 μm. These particles consist essentially of a wax or a mixture of waxes. The melting point of the wax or wax mixture is preferably between 50 ° C and 150 ° C. In addition, the particles of the microdispersion may contain in a minor proportion oily or pasty fatty additives, one or more surfactants and one or more usual fat-soluble active ingredients, as will be specified below.

The composition generally contains from 0.1 to 40% by weight of waxes, in particular from 5 to 30%, and a quantity of sufficient of at least one emulsifier. The amount of emulsifier is an amount sufficient to obtain a microdispersion of wax as defined above. This sufficient amount can be determined in each case by routine experiments.

Waxes are natural substances (animal or plant) or synthetic solid at room temperature (20 ° -25 ° C). They are insoluble in water, soluble in oils and are capable of forming a water-repellent film.

On the definition of waxes, we can mention for example PD Dorgan, Drug and Cosmetic Industry, December 1983, pp. 30-33 .

The wax or waxes constituting the waxy mixture are chosen in particular from carnauba wax, candelilla wax, and alfa wax, and mixtures thereof.

• la cire de paraffine
• l'ozokérite
• les cires végétales comme la cire d'olivier, la cire de riz, la cire de jojoba hydrogénée ou les cires absolues de fleurs telles que la cire essentielle de fleur de cassis vendue par la Société BERTIN (France).
• les cires animales comme les cires d'abeilles, ou les cires d'abeilles modifiées (cerabellina) ;
• d'autres cires ou matières premières cireuses : les cires marines telles que celle vendue par la Société SOPHIM sous la référence M82, les céramides naturels ou de synthèse, ou les cires de polyéthylène ou de polyoléfines en général.

In addition to the waxes mentioned above, the wax mixture may also contain one or more of the following waxes or families of waxes:

• paraffin wax
• ozokerite
• vegetable waxes such as olive wax, rice wax, hydrogenated jojoba wax or absolute waxes of flowers such as essential wax of blackcurrant sold by BERTIN (France).
• animal waxes such as bees waxes, or modified beeswaxes (cerabellina);
• other waxes or waxy raw materials: marine waxes such as that sold by SOPHIM under the reference M82, natural or synthetic ceramides, or polyethylene waxes or polyolefins in general.

The vegetable waxes of Carnauba (extracted from Copernica Cerifera), Candelilla (extracted from Euphobies Cerifera and Pedilantus pavonis) and Alfa (extracted from Stipa tenacissima), are commercial products.

Ceramides are the main constituent lipids of the intercoméocyte spaces of the Stratum Comeum. They are described in particular by Downing in Science, 1982, vol. 18, P. 1261-1262 . Synthetic analogs are also known, such as HO3 ceramides sold by COSMIND.

In the wax mixture, the Carnauba wax and / or Candelilla wax and / or Alfa wax represents at least 20%, and preferably at least 50% by weight relative to the total weight of the wax mixture.

The wax or the mixture of waxes may contain, in addition to the waxes mentioned above, at least one other wax and / or at least one oil, it being understood that the mixture of waxes and optionally of oil has a higher melting point. at 50 ° C.

• les huiles végétales comme l'huile de tournesol, l'huile dejojoba, etc.;
• les huiles minérales comme l'huile de paraffine ;
• les huiles de silicones fluides de viscosité comprise notamment entre 0.65 et 100.000 centistokes (soit entre 0,65.10^-4 et 10m².s^-1, de préférence entre 5 et 5000 centistokes (soit entre 5.10^-4 et 5.10^-1m².s^-1) ;
• les huiles fluorées ;
• la vaseline ;
• la lanoline.

The mixture of waxes can therefore be combined with one or more fatty additives (oily or pasty). We will quote in a non restrictive way:

• vegetable oils such as sunflower oil, dejojoba oil, etc .;
• mineral oils such as paraffin oil;
• fluid silicone oils with a viscosity of in particular between 0.65 and 100,000 centistokes (ie between 0.65 × 10 ^-4 and 10 m ² · s ^-1 , preferably between 5 and 5000 centistokes (ie between 5.10 ^-4 and 5.10 ^-1 m ²⁾ . s ^-1 );
• fluorinated oils;
• petrolatum;
• the lanolin.

The mixture of oil (s) and / or pasty fatty additives can represent up to 30%, preferably at most 10%, of the weight of waxes.

It is also possible to introduce liposoluble active ingredients into the microparticulate waxy phase.

When present, the liposoluble active ingredient (s) represent at most 30%, preferably at most 10%, of the weight of the microparticles.

The use of surfactants as emulsifiers in the preparation of microdispersions of waxes is known. The microdispersion can be carried out using anionic, cationic and / or nonionic surfactants in a known manner.

The percentage of surfactant (s) in the final composition is generally between about 0.01 and 25% and in particular may vary from 0.1 to 10%.

The weight ratio wax (s) / emulsifier (s) may vary for example in the range of 1 to 30 and in particular from 2 to 10.

The anionic surfactants used are in particular salts of fatty acids (for example alkaline salts or organic salts such as amine salts), said fatty acids having, for example, from 12 to 16 carbon atoms and which may comprise a double bond as in the case of oleic acid, alkaline salts or organic base salts of alkyl-sulfuric and alkylsulphonic acids having 12 to 18 carbon atoms, alkyl-arylsulphonic acids whose alkyl chain contains from 6 to 18 carbon atoms, the aryl group being for example a phenyl group. They are also the ether-sulfates, in particular the sulfation products of polyalkoxylated alkylphenol fatty alcohols in which the aliphatic chain comprises from 6 to 20 carbon atoms and the polyalkoxylated chain of 1 to 30 oxyalkylene units, in particular oxyethylene, oxypropylene or oxybutylene .

All of these anionic surfactants are well known and many of them are commercial products.

The nonionic surfactants are mainly polyalkoxylated and / or polyglycerolated surfactants. These include fatty acids or polyalkoxylated and / or polyglycerolated fatty acid amides; fatty alcohols or polyalkoxylated and / or polyglycerolated alkylphenols; esters of polyalkoxylated and / or polyglycerolated fatty acids and polyols; polyalkoxylated and / or polyglycerolated 1,2-alkanediols or 1,2-alkenediols; and polyalkoxylated and / or polyglycerolated 1,2-alkanediols or 1,2-alkenediols. For example, the fatty acids or fatty alcohols, optionally unsaturated, have 12 to 24 carbon atoms, the alkyl chain of the alkylphenols has 6 to 16 carbon atoms, the alkanediols or alkenediols have from 9 to 24 carbon atoms, the alkyl of alkylethers has from 4 to 20 carbon atoms, and the number of oxyalkylene units or units (CH ₂ CHOHCH ₂ O) can range from 2 to 40.

The polyalkoxylated nonionic derivatives are in particular polyoxyethylenated derivatives, optionally polyoxypropylenated.

The polyalkoxylated fatty acids are commercial products, in particular the products sold under the trademark Myrj by the company ATLAS.

The fatty acid esters and polyoxyethylenated polyols for which the polyol is sorbitol are known products (Polysorbate and products sold under the brand Tween by ATLAS). When the polyol is glycerol, it is possible to use the products marketed under the trademark Brij by the company ATLAS.

The polyglycerolated fatty alcohols, the polyglycerolated alkanediols or alkanediols, or the polyglycerolated alkanediols or alkanediols may be prepared, for example, according to the processes described in the French patents. 1477048 , 2025681 , 2091516 and 2,465,780 or according to analogous methods.

The fatty acids or amides of polyglycerolated fatty acids are described in particular in French patent 1,484,723 or are still commercial products such as those sold under the brand name PLUROL (Gattefossé) or DREWPOL, (Stefan Company), or DECAGLYN (Nikko Chemical).

• les alkylcarbamates de triglycérol de formule générale :
  
          R-NHCOOCH(CH₂OCH₂CHOHCH₂OH)₂
  
  dans laquelle R représente un groupe alkyle saturé ou non de 10 à 20 atomes de carbone. Ces composés sont décrits dans le brevet EP 0420761 ;
• les dérivés oxyéthylénés ou propoxylés des alcools de la lanoline, des acides gras de la lanoline, ou de leur mélanges.

Other nonionic surfactants that can be used are, for example:

• triglycerol alkylcarbamates of the general formula:
  
  R-NHCOOCH (CH ₂ OCH ₂ CHOHCH ₂ OH) ₂
  
  in which R represents a saturated or unsaturated alkyl group of 10 to 20 carbon atoms. These compounds are described in EP 0420761 ;
• oxyethylenated or propoxylated derivatives of lanolin alcohols, lanolin fatty acids, or mixtures thereof.

Such surfactants are marketed by Amerchol under the trademark Solulan.

Anionic surfactants include quaternary ammonium compounds such as ARQUAD 16-50, ARQUAD 18-50, ARQUAD T-50, ARQUAD 2C-75, ETHOAQUAD c / 12, and the like. ETHOQUAD O / 12, marketed by Armak Chemicals.

The use of nonionic surfactants is preferred.

It is also possible to prepare microdispersions of waxes using commercial mixtures of self-emulsifiable waxes containing the wax and the surfactants.

For example, the wax marketed under the name "SIRE AUTO LUSTRANTE OFR" by the company TISCCO, which contains carnauba and paraffin waxes, in combination with non-ionic emulsifiers, or the self-emulsifiable wax marketed under the name CERAX may be used. AO 28 / B by LA CERESINE, which contains Alfa wax in combination with a nonionic emulsifier.

These commercial mixtures make it possible to prepare microdispersions of waxes by adding water according to the process described above.

It is also possible to use microdispersions of ready-to-use waxes commercially available, such as the products of the SLIP-AID series from DANIEL PRODUCTS COMPANY, or the Aquacer products from CERACHEMIE.

The microdispersions of waxes are dilutable with water without affecting the stability of the microdispersion. They can therefore be in the form of concentrated compositions whose proportion of ingredients can be adjusted to a desired value by simply adding water.

The composition contains a cosmetically or dermatologically acceptable medium, that is to say compatible with the cutaneous tissues. Thus, the composition can be applied to the entire human body.

In known manner, the cosmetic or dermatological composition of the invention may also contain adjuvants usual in the cosmetic, pharmaceutical or dermatological field, such as hydrophilic or lipophilic gelling agents, hydrophilic or lipophilic active agents, preservatives, antioxidants, solvents , perfumes, fillers, filters, bactericides, odor absorbers and dyestuffs. The amounts of these various adjuvants are those conventionally used in the field under consideration, and for example from 0.01% to 10% of the total weight of the composition. These adjuvants, depending on their nature, can be introduced into the fatty phase, into the aqueous phase and / or into the lipid spherules.

As solvents that can be used in the invention, mention may be made of lower alcohols, in particular ethanol and isopropanol, and propylene glycol.

As hydrophilic gelling agents, mention may be made of carboxyvinyl polymers (carbomer), acrylic copolymers such as acrylate / alkylacrylate copolymers, polyacrylamides, polysaccharides such as hydroxypropylcellulose, natural gums and clays, and, as lipophilic gelling agents there may be mentioned modified clays such as bentones, metal salts of fatty acids such as aluminum stearates and hydrophobic silica, or ethylcellulose or polyethylene.

As lipophilic or hydrophilic active agents that can be used in the invention in order to perfect the treatment of wrinkles, fine lines, the fight against sagging skin and / or subcutaneous and / or the radiance of the skin, mention may for example be made of retinoids (retinol and its esters, retinal, retinoic acid and its derivatives, retinoids, especially those described in the documents FR-A-2,570,377 , EP-A-199636 , EP-A-325540 , EP-A-402072 ), α-hydroxy-acids (glycolic, lactic, malic, citric, tartaric, mandelic), β-hydroxy-acids (salicylic acid and its derivatives in particular alkylated), α-keto acids, β-keto- acids, peroxides such as benzoyl peroxide, vitamins including E, F, anti-radical active agents such as superoxide dismutase, selenium, zinc, beta-carotenes, tensor polymers of natural or synthetic origin.

The composition may further contain natural or synthetic, estrogenic, progestational or androgenic hormones such as progesterone, testosterone, anhydrous estradiol, broparestrol, estrone, pregnenolone acetate, pregnenolone, 17 beta-hydroxy - progesterone, testosterone propionate, androstenedione and androstanediols.

The compositions according to the invention are obtained by hot formation of a microemulsion. More specifically, these compositions are obtained by a process mainly characterized by the fact that the wax and the emulsifier are heated to a temperature above the melting temperature of the wax and not higher than 100 ° C., optionally in the presence of part of the water, until the wax has melted completely, the water, or the remainder of the water, is progressively added to a temperature at least equal to the said temperature, with stirring, until for forming a wax microemulsion in a continuous aqueous phase and then allowed to cool to room temperature. A stable microdispersion of wax is obtained.

Agitation and an amount of surfactant are sufficient so that the dimensions of wax microparticles are less than 1000 nm, and preferably 500 nm.

Fat-soluble ingredients, for example ceramides, are generally added to the wax prior to making the microdispersion.

The water-soluble ingredients may be added in the water used to make the microdispersion, or in the wax microdispersion finally obtained.

Similarly, the secondary ingredients optionally present in the composition are added according to the case either in the starting materials or in the finished composition.

The following examples are given by way of illustration of the invention. The percentages are given by weight of raw material relative to the total weight of the composition. The names of the constituents are given in INCI name.

Example 1 Antiwrinkle Cream (Water-in-Oil Emulsion)

Phase A: Hydrogenated polyisobutene 5.5% Isostearyl neopentanoate 3.5% PEG-20 stearate 1% Glyceryl stearate and PEG-100 stearate 2% Cetyl alcohol 0,5% Stearyl alcohol 0,5% Stearic acid 3% Phase A ': cyclomethicone 11% Phase C: Polyacrylamide and C13-C14 isoparaffin and laureth-7 1.7% Phase D: Polyethylene (AQUACER 513 sold by the company CERACHIMIE) 20% Phase B: conservatives qs Sodium hydroxide 0.03% Water qsp 100%

Operating mode:

Phase A is heated with stirring until homogeneous. After cooling, phase A 'is added. The phase B is heated with stirring, then poured into B always with stirring. After cooling to 50 ° C., phase C is incorporated in the emulsion and phase D is then added at 40 ° C.

Example 2 Anti-Aging Serum

Polyacrylamide and C13-C14 isoparaffin and laureth-7 1% Xanthan gum 0.2% PVM / MA Decadiene Crosspolymer 0.2% triethanolamine 0.2% Polyethylene (AQUACER 513 sold by the company CERACHIMIE) 10% Tory qs Water qsp 100%

Procedure: The xanthan gum and the polymer (PVM / MA Decadiene Crosspolymer) are dispersed in hot water while stirring with preservatives and triethanolamine. It is cooled to 40 ° C. and the microcircle (polyethylene) and the polyacrylamide are incorporated, still stirring.

Claims (5)

1. Cosmetic use of a microdispersion of wax in which the particles are less than 1 µm in size, as an active agent intended to prevent and/or treat the appearance of wrinkles and/or fine lines.
2. Use according to Claim 1, characterized in that the particles in the microdispersion of wax are less than or equal to 0.5 µm in size.
3. Use according to either one of Claims 1 and 2 above, characterized in that the particles in the microdispersion of wax consist essentially of a wax or of a mixture of waxes whose melting point is between 50°C and 150°C.
4. Cosmetic process for reviving the radiance of the skin by treating wrinkles and/or fine lines while using a microdispersion of wax in which the particles are less than 1 µm in size, which is applied to the skin in a cosmetic composition.
5. Process according to Claim 4, characterized in that the composition contains from 0.1 to 40% by weight of waxes, in particular 5 to 30%.